xref: /openbmc/linux/drivers/media/pci/ivtv/ivtv-i2c.c (revision b830f94f)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3     I2C functions
4     Copyright (C) 2003-2004  Kevin Thayer <nufan_wfk at yahoo.com>
5     Copyright (C) 2005-2007  Hans Verkuil <hverkuil@xs4all.nl>
6 
7  */
8 
9 /*
10     This file includes an i2c implementation that was reverse engineered
11     from the Hauppauge windows driver.  Older ivtv versions used i2c-algo-bit,
12     which whilst fine under most circumstances, had trouble with the Zilog
13     CPU on the PVR-150 which handles IR functions (occasional inability to
14     communicate with the chip until it was reset) and also with the i2c
15     bus being completely unreachable when multiple PVR cards were present.
16 
17     The implementation is very similar to i2c-algo-bit, but there are enough
18     subtle differences that the two are hard to merge.  The general strategy
19     employed by i2c-algo-bit is to use udelay() to implement the timing
20     when putting out bits on the scl/sda lines.  The general strategy taken
21     here is to poll the lines for state changes (see ivtv_waitscl and
22     ivtv_waitsda).  In addition there are small delays at various locations
23     which poll the SCL line 5 times (ivtv_scldelay).  I would guess that
24     since this is memory mapped I/O that the length of those delays is tied
25     to the PCI bus clock.  There is some extra code to do with recovery
26     and retries.  Since it is not known what causes the actual i2c problems
27     in the first place, the only goal if one was to attempt to use
28     i2c-algo-bit would be to try to make it follow the same code path.
29     This would be a lot of work, and I'm also not convinced that it would
30     provide a generic benefit to i2c-algo-bit.  Therefore consider this
31     an engineering solution -- not pretty, but it works.
32 
33     Some more general comments about what we are doing:
34 
35     The i2c bus is a 2 wire serial bus, with clock (SCL) and data (SDA)
36     lines.  To communicate on the bus (as a master, we don't act as a slave),
37     we first initiate a start condition (ivtv_start).  We then write the
38     address of the device that we want to communicate with, along with a flag
39     that indicates whether this is a read or a write.  The slave then issues
40     an ACK signal (ivtv_ack), which tells us that it is ready for reading /
41     writing.  We then proceed with reading or writing (ivtv_read/ivtv_write),
42     and finally issue a stop condition (ivtv_stop) to make the bus available
43     to other masters.
44 
45     There is an additional form of transaction where a write may be
46     immediately followed by a read.  In this case, there is no intervening
47     stop condition.  (Only the msp3400 chip uses this method of data transfer).
48  */
49 
50 #include "ivtv-driver.h"
51 #include "ivtv-cards.h"
52 #include "ivtv-gpio.h"
53 #include "ivtv-i2c.h"
54 #include <media/drv-intf/cx25840.h>
55 
56 /* i2c implementation for cx23415/6 chip, ivtv project.
57  * Author: Kevin Thayer (nufan_wfk at yahoo.com)
58  */
59 /* i2c stuff */
60 #define IVTV_REG_I2C_SETSCL_OFFSET 0x7000
61 #define IVTV_REG_I2C_SETSDA_OFFSET 0x7004
62 #define IVTV_REG_I2C_GETSCL_OFFSET 0x7008
63 #define IVTV_REG_I2C_GETSDA_OFFSET 0x700c
64 
65 #define IVTV_CS53L32A_I2C_ADDR		0x11
66 #define IVTV_M52790_I2C_ADDR		0x48
67 #define IVTV_CX25840_I2C_ADDR		0x44
68 #define IVTV_SAA7115_I2C_ADDR		0x21
69 #define IVTV_SAA7127_I2C_ADDR		0x44
70 #define IVTV_SAA717x_I2C_ADDR		0x21
71 #define IVTV_MSP3400_I2C_ADDR		0x40
72 #define IVTV_HAUPPAUGE_I2C_ADDR		0x50
73 #define IVTV_WM8739_I2C_ADDR		0x1a
74 #define IVTV_WM8775_I2C_ADDR		0x1b
75 #define IVTV_TEA5767_I2C_ADDR		0x60
76 #define IVTV_UPD64031A_I2C_ADDR		0x12
77 #define IVTV_UPD64083_I2C_ADDR		0x5c
78 #define IVTV_VP27SMPX_I2C_ADDR		0x5b
79 #define IVTV_M52790_I2C_ADDR		0x48
80 #define IVTV_AVERMEDIA_IR_RX_I2C_ADDR	0x40
81 #define IVTV_HAUP_EXT_IR_RX_I2C_ADDR	0x1a
82 #define IVTV_HAUP_INT_IR_RX_I2C_ADDR	0x18
83 #define IVTV_Z8F0811_IR_TX_I2C_ADDR	0x70
84 #define IVTV_Z8F0811_IR_RX_I2C_ADDR	0x71
85 #define IVTV_ADAPTEC_IR_ADDR		0x6b
86 
87 /* This array should match the IVTV_HW_ defines */
88 static const u8 hw_addrs[] = {
89 	IVTV_CX25840_I2C_ADDR,
90 	IVTV_SAA7115_I2C_ADDR,
91 	IVTV_SAA7127_I2C_ADDR,
92 	IVTV_MSP3400_I2C_ADDR,
93 	0,
94 	IVTV_WM8775_I2C_ADDR,
95 	IVTV_CS53L32A_I2C_ADDR,
96 	0,
97 	IVTV_SAA7115_I2C_ADDR,
98 	IVTV_UPD64031A_I2C_ADDR,
99 	IVTV_UPD64083_I2C_ADDR,
100 	IVTV_SAA717x_I2C_ADDR,
101 	IVTV_WM8739_I2C_ADDR,
102 	IVTV_VP27SMPX_I2C_ADDR,
103 	IVTV_M52790_I2C_ADDR,
104 	0,				/* IVTV_HW_GPIO dummy driver ID */
105 	IVTV_AVERMEDIA_IR_RX_I2C_ADDR,	/* IVTV_HW_I2C_IR_RX_AVER */
106 	IVTV_HAUP_EXT_IR_RX_I2C_ADDR,	/* IVTV_HW_I2C_IR_RX_HAUP_EXT */
107 	IVTV_HAUP_INT_IR_RX_I2C_ADDR,	/* IVTV_HW_I2C_IR_RX_HAUP_INT */
108 	IVTV_Z8F0811_IR_RX_I2C_ADDR,	/* IVTV_HW_Z8F0811_IR_HAUP */
109 	IVTV_ADAPTEC_IR_ADDR,		/* IVTV_HW_I2C_IR_RX_ADAPTEC */
110 };
111 
112 /* This array should match the IVTV_HW_ defines */
113 static const char * const hw_devicenames[] = {
114 	"cx25840",
115 	"saa7115",
116 	"saa7127_auto",	/* saa7127 or saa7129 */
117 	"msp3400",
118 	"tuner",
119 	"wm8775",
120 	"cs53l32a",
121 	"tveeprom",
122 	"saa7114",
123 	"upd64031a",
124 	"upd64083",
125 	"saa717x",
126 	"wm8739",
127 	"vp27smpx",
128 	"m52790",
129 	"gpio",
130 	"ir_video",		/* IVTV_HW_I2C_IR_RX_AVER */
131 	"ir_video",		/* IVTV_HW_I2C_IR_RX_HAUP_EXT */
132 	"ir_video",		/* IVTV_HW_I2C_IR_RX_HAUP_INT */
133 	"ir_z8f0811_haup",	/* IVTV_HW_Z8F0811_IR_HAUP */
134 	"ir_video",		/* IVTV_HW_I2C_IR_RX_ADAPTEC */
135 };
136 
137 static int get_key_adaptec(struct IR_i2c *ir, enum rc_proto *protocol,
138 			   u32 *scancode, u8 *toggle)
139 {
140 	unsigned char keybuf[4];
141 
142 	keybuf[0] = 0x00;
143 	i2c_master_send(ir->c, keybuf, 1);
144 	/* poll IR chip */
145 	if (i2c_master_recv(ir->c, keybuf, sizeof(keybuf)) != sizeof(keybuf)) {
146 		return 0;
147 	}
148 
149 	/* key pressed ? */
150 	if (keybuf[2] == 0xff)
151 		return 0;
152 
153 	/* remove repeat bit */
154 	keybuf[2] &= 0x7f;
155 	keybuf[3] |= 0x80;
156 
157 	*protocol = RC_PROTO_UNKNOWN;
158 	*scancode = keybuf[3] | keybuf[2] << 8 | keybuf[1] << 16 |keybuf[0] << 24;
159 	*toggle = 0;
160 	return 1;
161 }
162 
163 static int ivtv_i2c_new_ir(struct ivtv *itv, u32 hw, const char *type, u8 addr)
164 {
165 	struct i2c_board_info info;
166 	struct i2c_adapter *adap = &itv->i2c_adap;
167 	struct IR_i2c_init_data *init_data = &itv->ir_i2c_init_data;
168 	unsigned short addr_list[2] = { addr, I2C_CLIENT_END };
169 
170 	/* Only allow one IR receiver to be registered per board */
171 	if (itv->hw_flags & IVTV_HW_IR_ANY)
172 		return -1;
173 
174 	/* Our default information for ir-kbd-i2c.c to use */
175 	switch (hw) {
176 	case IVTV_HW_I2C_IR_RX_AVER:
177 		init_data->ir_codes = RC_MAP_AVERMEDIA_CARDBUS;
178 		init_data->internal_get_key_func =
179 					IR_KBD_GET_KEY_AVERMEDIA_CARDBUS;
180 		init_data->type = RC_PROTO_BIT_OTHER;
181 		init_data->name = "AVerMedia AVerTV card";
182 		break;
183 	case IVTV_HW_I2C_IR_RX_HAUP_EXT:
184 	case IVTV_HW_I2C_IR_RX_HAUP_INT:
185 		init_data->ir_codes = RC_MAP_HAUPPAUGE;
186 		init_data->internal_get_key_func = IR_KBD_GET_KEY_HAUP;
187 		init_data->type = RC_PROTO_BIT_RC5;
188 		init_data->name = itv->card_name;
189 		break;
190 	case IVTV_HW_Z8F0811_IR_HAUP:
191 		/* Default to grey remote */
192 		init_data->ir_codes = RC_MAP_HAUPPAUGE;
193 		init_data->internal_get_key_func = IR_KBD_GET_KEY_HAUP_XVR;
194 		init_data->type = RC_PROTO_BIT_RC5 | RC_PROTO_BIT_RC6_MCE |
195 							RC_PROTO_BIT_RC6_6A_32;
196 		init_data->name = itv->card_name;
197 		break;
198 	case IVTV_HW_I2C_IR_RX_ADAPTEC:
199 		init_data->get_key = get_key_adaptec;
200 		init_data->name = itv->card_name;
201 		/* FIXME: The protocol and RC_MAP needs to be corrected */
202 		init_data->ir_codes = RC_MAP_EMPTY;
203 		init_data->type = RC_PROTO_BIT_UNKNOWN;
204 		break;
205 	}
206 
207 	memset(&info, 0, sizeof(struct i2c_board_info));
208 	info.platform_data = init_data;
209 	strscpy(info.type, type, I2C_NAME_SIZE);
210 
211 	return i2c_new_probed_device(adap, &info, addr_list, NULL) == NULL ?
212 	       -1 : 0;
213 }
214 
215 /* Instantiate the IR receiver device using probing -- undesirable */
216 struct i2c_client *ivtv_i2c_new_ir_legacy(struct ivtv *itv)
217 {
218 	struct i2c_board_info info;
219 	/*
220 	 * The external IR receiver is at i2c address 0x34.
221 	 * The internal IR receiver is at i2c address 0x30.
222 	 *
223 	 * In theory, both can be fitted, and Hauppauge suggests an external
224 	 * overrides an internal.  That's why we probe 0x1a (~0x34) first. CB
225 	 *
226 	 * Some of these addresses we probe may collide with other i2c address
227 	 * allocations, so this function must be called after all other i2c
228 	 * devices we care about are registered.
229 	 */
230 	static const unsigned short addr_list[] = {
231 		0x1a,	/* Hauppauge IR external - collides with WM8739 */
232 		0x18,	/* Hauppauge IR internal */
233 		I2C_CLIENT_END
234 	};
235 
236 	memset(&info, 0, sizeof(struct i2c_board_info));
237 	strscpy(info.type, "ir_video", I2C_NAME_SIZE);
238 	return i2c_new_probed_device(&itv->i2c_adap, &info, addr_list, NULL);
239 }
240 
241 int ivtv_i2c_register(struct ivtv *itv, unsigned idx)
242 {
243 	struct v4l2_subdev *sd;
244 	struct i2c_adapter *adap = &itv->i2c_adap;
245 	const char *type = hw_devicenames[idx];
246 	u32 hw = 1 << idx;
247 
248 	if (hw == IVTV_HW_TUNER) {
249 		/* special tuner handling */
250 		sd = v4l2_i2c_new_subdev(&itv->v4l2_dev, adap, type, 0,
251 				itv->card_i2c->radio);
252 		if (sd)
253 			sd->grp_id = 1 << idx;
254 		sd = v4l2_i2c_new_subdev(&itv->v4l2_dev, adap, type, 0,
255 				itv->card_i2c->demod);
256 		if (sd)
257 			sd->grp_id = 1 << idx;
258 		sd = v4l2_i2c_new_subdev(&itv->v4l2_dev, adap, type, 0,
259 				itv->card_i2c->tv);
260 		if (sd)
261 			sd->grp_id = 1 << idx;
262 		return sd ? 0 : -1;
263 	}
264 
265 	if (hw & IVTV_HW_IR_ANY)
266 		return ivtv_i2c_new_ir(itv, hw, type, hw_addrs[idx]);
267 
268 	/* Is it not an I2C device or one we do not wish to register? */
269 	if (!hw_addrs[idx])
270 		return -1;
271 
272 	/* It's an I2C device other than an analog tuner or IR chip */
273 	if (hw == IVTV_HW_UPD64031A || hw == IVTV_HW_UPD6408X) {
274 		sd = v4l2_i2c_new_subdev(&itv->v4l2_dev,
275 				adap, type, 0, I2C_ADDRS(hw_addrs[idx]));
276 	} else if (hw == IVTV_HW_CX25840) {
277 		struct cx25840_platform_data pdata;
278 		struct i2c_board_info cx25840_info = {
279 			.type = "cx25840",
280 			.addr = hw_addrs[idx],
281 			.platform_data = &pdata,
282 		};
283 
284 		memset(&pdata, 0, sizeof(pdata));
285 		pdata.pvr150_workaround = itv->pvr150_workaround;
286 		sd = v4l2_i2c_new_subdev_board(&itv->v4l2_dev, adap,
287 				&cx25840_info, NULL);
288 	} else {
289 		sd = v4l2_i2c_new_subdev(&itv->v4l2_dev,
290 				adap, type, hw_addrs[idx], NULL);
291 	}
292 	if (sd)
293 		sd->grp_id = 1 << idx;
294 	return sd ? 0 : -1;
295 }
296 
297 struct v4l2_subdev *ivtv_find_hw(struct ivtv *itv, u32 hw)
298 {
299 	struct v4l2_subdev *result = NULL;
300 	struct v4l2_subdev *sd;
301 
302 	spin_lock(&itv->v4l2_dev.lock);
303 	v4l2_device_for_each_subdev(sd, &itv->v4l2_dev) {
304 		if (sd->grp_id == hw) {
305 			result = sd;
306 			break;
307 		}
308 	}
309 	spin_unlock(&itv->v4l2_dev.lock);
310 	return result;
311 }
312 
313 /* Set the serial clock line to the desired state */
314 static void ivtv_setscl(struct ivtv *itv, int state)
315 {
316 	/* write them out */
317 	/* write bits are inverted */
318 	write_reg(~state, IVTV_REG_I2C_SETSCL_OFFSET);
319 }
320 
321 /* Set the serial data line to the desired state */
322 static void ivtv_setsda(struct ivtv *itv, int state)
323 {
324 	/* write them out */
325 	/* write bits are inverted */
326 	write_reg(~state & 1, IVTV_REG_I2C_SETSDA_OFFSET);
327 }
328 
329 /* Read the serial clock line */
330 static int ivtv_getscl(struct ivtv *itv)
331 {
332 	return read_reg(IVTV_REG_I2C_GETSCL_OFFSET) & 1;
333 }
334 
335 /* Read the serial data line */
336 static int ivtv_getsda(struct ivtv *itv)
337 {
338 	return read_reg(IVTV_REG_I2C_GETSDA_OFFSET) & 1;
339 }
340 
341 /* Implement a short delay by polling the serial clock line */
342 static void ivtv_scldelay(struct ivtv *itv)
343 {
344 	int i;
345 
346 	for (i = 0; i < 5; ++i)
347 		ivtv_getscl(itv);
348 }
349 
350 /* Wait for the serial clock line to become set to a specific value */
351 static int ivtv_waitscl(struct ivtv *itv, int val)
352 {
353 	int i;
354 
355 	ivtv_scldelay(itv);
356 	for (i = 0; i < 1000; ++i) {
357 		if (ivtv_getscl(itv) == val)
358 			return 1;
359 	}
360 	return 0;
361 }
362 
363 /* Wait for the serial data line to become set to a specific value */
364 static int ivtv_waitsda(struct ivtv *itv, int val)
365 {
366 	int i;
367 
368 	ivtv_scldelay(itv);
369 	for (i = 0; i < 1000; ++i) {
370 		if (ivtv_getsda(itv) == val)
371 			return 1;
372 	}
373 	return 0;
374 }
375 
376 /* Wait for the slave to issue an ACK */
377 static int ivtv_ack(struct ivtv *itv)
378 {
379 	int ret = 0;
380 
381 	if (ivtv_getscl(itv) == 1) {
382 		IVTV_DEBUG_HI_I2C("SCL was high starting an ack\n");
383 		ivtv_setscl(itv, 0);
384 		if (!ivtv_waitscl(itv, 0)) {
385 			IVTV_DEBUG_I2C("Could not set SCL low starting an ack\n");
386 			return -EREMOTEIO;
387 		}
388 	}
389 	ivtv_setsda(itv, 1);
390 	ivtv_scldelay(itv);
391 	ivtv_setscl(itv, 1);
392 	if (!ivtv_waitsda(itv, 0)) {
393 		IVTV_DEBUG_I2C("Slave did not ack\n");
394 		ret = -EREMOTEIO;
395 	}
396 	ivtv_setscl(itv, 0);
397 	if (!ivtv_waitscl(itv, 0)) {
398 		IVTV_DEBUG_I2C("Failed to set SCL low after ACK\n");
399 		ret = -EREMOTEIO;
400 	}
401 	return ret;
402 }
403 
404 /* Write a single byte to the i2c bus and wait for the slave to ACK */
405 static int ivtv_sendbyte(struct ivtv *itv, unsigned char byte)
406 {
407 	int i, bit;
408 
409 	IVTV_DEBUG_HI_I2C("write %x\n",byte);
410 	for (i = 0; i < 8; ++i, byte<<=1) {
411 		ivtv_setscl(itv, 0);
412 		if (!ivtv_waitscl(itv, 0)) {
413 			IVTV_DEBUG_I2C("Error setting SCL low\n");
414 			return -EREMOTEIO;
415 		}
416 		bit = (byte>>7)&1;
417 		ivtv_setsda(itv, bit);
418 		if (!ivtv_waitsda(itv, bit)) {
419 			IVTV_DEBUG_I2C("Error setting SDA\n");
420 			return -EREMOTEIO;
421 		}
422 		ivtv_setscl(itv, 1);
423 		if (!ivtv_waitscl(itv, 1)) {
424 			IVTV_DEBUG_I2C("Slave not ready for bit\n");
425 			return -EREMOTEIO;
426 		}
427 	}
428 	ivtv_setscl(itv, 0);
429 	if (!ivtv_waitscl(itv, 0)) {
430 		IVTV_DEBUG_I2C("Error setting SCL low\n");
431 		return -EREMOTEIO;
432 	}
433 	return ivtv_ack(itv);
434 }
435 
436 /* Read a byte from the i2c bus and send a NACK if applicable (i.e. for the
437    final byte) */
438 static int ivtv_readbyte(struct ivtv *itv, unsigned char *byte, int nack)
439 {
440 	int i;
441 
442 	*byte = 0;
443 
444 	ivtv_setsda(itv, 1);
445 	ivtv_scldelay(itv);
446 	for (i = 0; i < 8; ++i) {
447 		ivtv_setscl(itv, 0);
448 		ivtv_scldelay(itv);
449 		ivtv_setscl(itv, 1);
450 		if (!ivtv_waitscl(itv, 1)) {
451 			IVTV_DEBUG_I2C("Error setting SCL high\n");
452 			return -EREMOTEIO;
453 		}
454 		*byte = ((*byte)<<1)|ivtv_getsda(itv);
455 	}
456 	ivtv_setscl(itv, 0);
457 	ivtv_scldelay(itv);
458 	ivtv_setsda(itv, nack);
459 	ivtv_scldelay(itv);
460 	ivtv_setscl(itv, 1);
461 	ivtv_scldelay(itv);
462 	ivtv_setscl(itv, 0);
463 	ivtv_scldelay(itv);
464 	IVTV_DEBUG_HI_I2C("read %x\n",*byte);
465 	return 0;
466 }
467 
468 /* Issue a start condition on the i2c bus to alert slaves to prepare for
469    an address write */
470 static int ivtv_start(struct ivtv *itv)
471 {
472 	int sda;
473 
474 	sda = ivtv_getsda(itv);
475 	if (sda != 1) {
476 		IVTV_DEBUG_HI_I2C("SDA was low at start\n");
477 		ivtv_setsda(itv, 1);
478 		if (!ivtv_waitsda(itv, 1)) {
479 			IVTV_DEBUG_I2C("SDA stuck low\n");
480 			return -EREMOTEIO;
481 		}
482 	}
483 	if (ivtv_getscl(itv) != 1) {
484 		ivtv_setscl(itv, 1);
485 		if (!ivtv_waitscl(itv, 1)) {
486 			IVTV_DEBUG_I2C("SCL stuck low at start\n");
487 			return -EREMOTEIO;
488 		}
489 	}
490 	ivtv_setsda(itv, 0);
491 	ivtv_scldelay(itv);
492 	return 0;
493 }
494 
495 /* Issue a stop condition on the i2c bus to release it */
496 static int ivtv_stop(struct ivtv *itv)
497 {
498 	int i;
499 
500 	if (ivtv_getscl(itv) != 0) {
501 		IVTV_DEBUG_HI_I2C("SCL not low when stopping\n");
502 		ivtv_setscl(itv, 0);
503 		if (!ivtv_waitscl(itv, 0)) {
504 			IVTV_DEBUG_I2C("SCL could not be set low\n");
505 		}
506 	}
507 	ivtv_setsda(itv, 0);
508 	ivtv_scldelay(itv);
509 	ivtv_setscl(itv, 1);
510 	if (!ivtv_waitscl(itv, 1)) {
511 		IVTV_DEBUG_I2C("SCL could not be set high\n");
512 		return -EREMOTEIO;
513 	}
514 	ivtv_scldelay(itv);
515 	ivtv_setsda(itv, 1);
516 	if (!ivtv_waitsda(itv, 1)) {
517 		IVTV_DEBUG_I2C("resetting I2C\n");
518 		for (i = 0; i < 16; ++i) {
519 			ivtv_setscl(itv, 0);
520 			ivtv_scldelay(itv);
521 			ivtv_setscl(itv, 1);
522 			ivtv_scldelay(itv);
523 			ivtv_setsda(itv, 1);
524 		}
525 		ivtv_waitsda(itv, 1);
526 		return -EREMOTEIO;
527 	}
528 	return 0;
529 }
530 
531 /* Write a message to the given i2c slave.  do_stop may be 0 to prevent
532    issuing the i2c stop condition (when following with a read) */
533 static int ivtv_write(struct ivtv *itv, unsigned char addr, unsigned char *data, u32 len, int do_stop)
534 {
535 	int retry, ret = -EREMOTEIO;
536 	u32 i;
537 
538 	for (retry = 0; ret != 0 && retry < 8; ++retry) {
539 		ret = ivtv_start(itv);
540 
541 		if (ret == 0) {
542 			ret = ivtv_sendbyte(itv, addr<<1);
543 			for (i = 0; ret == 0 && i < len; ++i)
544 				ret = ivtv_sendbyte(itv, data[i]);
545 		}
546 		if (ret != 0 || do_stop) {
547 			ivtv_stop(itv);
548 		}
549 	}
550 	if (ret)
551 		IVTV_DEBUG_I2C("i2c write to %x failed\n", addr);
552 	return ret;
553 }
554 
555 /* Read data from the given i2c slave.  A stop condition is always issued. */
556 static int ivtv_read(struct ivtv *itv, unsigned char addr, unsigned char *data, u32 len)
557 {
558 	int retry, ret = -EREMOTEIO;
559 	u32 i;
560 
561 	for (retry = 0; ret != 0 && retry < 8; ++retry) {
562 		ret = ivtv_start(itv);
563 		if (ret == 0)
564 			ret = ivtv_sendbyte(itv, (addr << 1) | 1);
565 		for (i = 0; ret == 0 && i < len; ++i) {
566 			ret = ivtv_readbyte(itv, &data[i], i == len - 1);
567 		}
568 		ivtv_stop(itv);
569 	}
570 	if (ret)
571 		IVTV_DEBUG_I2C("i2c read from %x failed\n", addr);
572 	return ret;
573 }
574 
575 /* Kernel i2c transfer implementation.  Takes a number of messages to be read
576    or written.  If a read follows a write, this will occur without an
577    intervening stop condition */
578 static int ivtv_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
579 {
580 	struct v4l2_device *v4l2_dev = i2c_get_adapdata(i2c_adap);
581 	struct ivtv *itv = to_ivtv(v4l2_dev);
582 	int retval;
583 	int i;
584 
585 	mutex_lock(&itv->i2c_bus_lock);
586 	for (i = retval = 0; retval == 0 && i < num; i++) {
587 		if (msgs[i].flags & I2C_M_RD)
588 			retval = ivtv_read(itv, msgs[i].addr, msgs[i].buf, msgs[i].len);
589 		else {
590 			/* if followed by a read, don't stop */
591 			int stop = !(i + 1 < num && msgs[i + 1].flags == I2C_M_RD);
592 
593 			retval = ivtv_write(itv, msgs[i].addr, msgs[i].buf, msgs[i].len, stop);
594 		}
595 	}
596 	mutex_unlock(&itv->i2c_bus_lock);
597 	return retval ? retval : num;
598 }
599 
600 /* Kernel i2c capabilities */
601 static u32 ivtv_functionality(struct i2c_adapter *adap)
602 {
603 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
604 }
605 
606 static const struct i2c_algorithm ivtv_algo = {
607 	.master_xfer   = ivtv_xfer,
608 	.functionality = ivtv_functionality,
609 };
610 
611 /* template for our-bit banger */
612 static const struct i2c_adapter ivtv_i2c_adap_hw_template = {
613 	.name = "ivtv i2c driver",
614 	.algo = &ivtv_algo,
615 	.algo_data = NULL,			/* filled from template */
616 	.owner = THIS_MODULE,
617 };
618 
619 static void ivtv_setscl_old(void *data, int state)
620 {
621 	struct ivtv *itv = (struct ivtv *)data;
622 
623 	if (state)
624 		itv->i2c_state |= 0x01;
625 	else
626 		itv->i2c_state &= ~0x01;
627 
628 	/* write them out */
629 	/* write bits are inverted */
630 	write_reg(~itv->i2c_state, IVTV_REG_I2C_SETSCL_OFFSET);
631 }
632 
633 static void ivtv_setsda_old(void *data, int state)
634 {
635 	struct ivtv *itv = (struct ivtv *)data;
636 
637 	if (state)
638 		itv->i2c_state |= 0x01;
639 	else
640 		itv->i2c_state &= ~0x01;
641 
642 	/* write them out */
643 	/* write bits are inverted */
644 	write_reg(~itv->i2c_state, IVTV_REG_I2C_SETSDA_OFFSET);
645 }
646 
647 static int ivtv_getscl_old(void *data)
648 {
649 	struct ivtv *itv = (struct ivtv *)data;
650 
651 	return read_reg(IVTV_REG_I2C_GETSCL_OFFSET) & 1;
652 }
653 
654 static int ivtv_getsda_old(void *data)
655 {
656 	struct ivtv *itv = (struct ivtv *)data;
657 
658 	return read_reg(IVTV_REG_I2C_GETSDA_OFFSET) & 1;
659 }
660 
661 /* template for i2c-bit-algo */
662 static const struct i2c_adapter ivtv_i2c_adap_template = {
663 	.name = "ivtv i2c driver",
664 	.algo = NULL,                   /* set by i2c-algo-bit */
665 	.algo_data = NULL,              /* filled from template */
666 	.owner = THIS_MODULE,
667 };
668 
669 #define IVTV_ALGO_BIT_TIMEOUT	(2)	/* seconds */
670 
671 static const struct i2c_algo_bit_data ivtv_i2c_algo_template = {
672 	.setsda		= ivtv_setsda_old,
673 	.setscl		= ivtv_setscl_old,
674 	.getsda		= ivtv_getsda_old,
675 	.getscl		= ivtv_getscl_old,
676 	.udelay		= IVTV_DEFAULT_I2C_CLOCK_PERIOD / 2,  /* microseconds */
677 	.timeout	= IVTV_ALGO_BIT_TIMEOUT * HZ,         /* jiffies */
678 };
679 
680 static const struct i2c_client ivtv_i2c_client_template = {
681 	.name = "ivtv internal",
682 };
683 
684 /* init + register i2c adapter */
685 int init_ivtv_i2c(struct ivtv *itv)
686 {
687 	int retval;
688 
689 	IVTV_DEBUG_I2C("i2c init\n");
690 
691 	/* Sanity checks for the I2C hardware arrays. They must be the
692 	 * same size.
693 	 */
694 	if (ARRAY_SIZE(hw_devicenames) != ARRAY_SIZE(hw_addrs)) {
695 		IVTV_ERR("Mismatched I2C hardware arrays\n");
696 		return -ENODEV;
697 	}
698 	if (itv->options.newi2c > 0) {
699 		itv->i2c_adap = ivtv_i2c_adap_hw_template;
700 	} else {
701 		itv->i2c_adap = ivtv_i2c_adap_template;
702 		itv->i2c_algo = ivtv_i2c_algo_template;
703 	}
704 	itv->i2c_algo.udelay = itv->options.i2c_clock_period / 2;
705 	itv->i2c_algo.data = itv;
706 	itv->i2c_adap.algo_data = &itv->i2c_algo;
707 
708 	sprintf(itv->i2c_adap.name + strlen(itv->i2c_adap.name), " #%d",
709 		itv->instance);
710 	i2c_set_adapdata(&itv->i2c_adap, &itv->v4l2_dev);
711 
712 	itv->i2c_client = ivtv_i2c_client_template;
713 	itv->i2c_client.adapter = &itv->i2c_adap;
714 	itv->i2c_adap.dev.parent = &itv->pdev->dev;
715 
716 	IVTV_DEBUG_I2C("setting scl and sda to 1\n");
717 	ivtv_setscl(itv, 1);
718 	ivtv_setsda(itv, 1);
719 
720 	if (itv->options.newi2c > 0)
721 		retval = i2c_add_adapter(&itv->i2c_adap);
722 	else
723 		retval = i2c_bit_add_bus(&itv->i2c_adap);
724 
725 	return retval;
726 }
727 
728 void exit_ivtv_i2c(struct ivtv *itv)
729 {
730 	IVTV_DEBUG_I2C("i2c exit\n");
731 
732 	i2c_del_adapter(&itv->i2c_adap);
733 }
734